1. Field of the Invention
This invention relates to delivery systems for water-insoluble active chemicals, and, more particularly, to a stable aqueous suspension concentrate of a UV-labile, water-insoluble biocide active concentrate to stabilize such actives against the degradation effects of sunlight and UV-radiation.
2. Description of the Prior Art
Numerous delivery systems and formulations have been proposed to provide aqueous dispersions of substantially water-insoluble biocide active chemicals such as iodopropargyl butyl carbamate (IPBC). For example U.S. Pat. No. 6,506,794 describes an aqueous dispersion of halopropargyl compounds and a partially hydrolyzed polyvinyl alcohol. However, such active dispersions are quite susceptible to degradation upon storage and/or exposure to UV-radiation. In particular, the decomposition of IPBC typically results in the formation of a yellow or brown by-product. The compositions thus will be unsuitable for use in certain systems in need of antimicrobial protection particularly white aqueous paints.
Various methods and compositions have been described to stabilize biocidal compositions containing IPBC, for example, using UV absorbers and/or organic epoxides in a liquid vehicle, as shown in U.S. Pat. Nos. 4,276,211; 4,552,885; 5,938,825; 6,059,991 and 6,140,370. U.S. Pat. No. 6,616,740 teaches on the use of various glycol carriers for IPBC stabilization. However, none of these disclosures provide a stable IPBC composition as an aqueous dispersion free from yellowing on exposure to UV-radiation.
U.S. Pat. No. 6,156,803 discloses the use of a partially neutralized alkyl vinyl ether-maleic acid half ester copolymer as a dispersing agent for water-insoluble agriculturally active chemicals. Published U.S. Patent Application US 2004/0024099 A1 describes an aqueous suspension concentrate for water insoluble chemicals comprising a mixture of an anionic polymeric suspension agent and a homo- and/or a co-polymer of a heterocyclic vinyl lactam.
Accordingly, it is an object of this invention to provide a stable, aqueous suspension concentrate of a UV-labile biocide active for delivery of such active in stabilized form into formulations and onto substrates.
A particular object herein is to provide such stable concentrates which experience substantially no degradation or coloration upon storage and/or exposure to sunlight or UV-radiation while retaining its bioactivity.